Equipment for winding material into core and coreless rolls is known in the art. For purposes of illustrating such prior art, one particular type of coreless plastic bag winder will be described, i.e., a winder for plastic garbage or trash bags, kitchen bags, wastebasket liners, food storage bags, etc.
In such a prior art winder, a continuous strip of bags is fed to the winder, and the winder prepares coreless rolls therefrom. The bags themselves are produced in upstream bag making equipment or on a separate piece of equipment, from which a continuous strip of bags is produced.
In most conventional bag making equipment a tube of plastic film is extruded through an extruding die, and the tube is then flattened before it enters the bag machine. In the bag machine the film is sealed across its width to form the bottom of the finished product. The open top of the bag can be formed in different ways. For example, the bag can simply be cut. In this type of bag machine, individual bags are formed which are typically folded and placed into suitable packaging for the individual or institutional consumer. In the other type of bag machine, the top is formed by perforating the bag across its width. The bag may then be folded longitudinally, either before or after the perforation step, to provide a continuous strip of connected and folded bags. Such bags are then wound into a core or coreless roll.
One prior art winder has been sold by CMD Corporation of Little Chute, Wis., the assignee of the present invention. Such winder includes a dancer mechanism to sense the tension of the strip of bags being fed to the winder. The dancer mechanism includes a connection to the winder drive motor, wherein the speed of the winder can be "slaved" to the output speed of an upstream bag making equipment.
The prior art winder also includes haul-off nip rollers, to feed the strip into the winder, and an interrupt section to periodically break the perforations between certain bags in the strip. The frequency of the interruption is determined by the number of bags to be included in each roll. For example, if the roll is to contain twenty bags, the interrupt section will break every twentieth perforation.
Downstream of these sections, the prior art winder includes a turret assembly with three spindles mounted 120.degree. apart. To begin winding a roll of bags the leading end of one strip of bags is directed to a first spindle when the turret is in a transfer position. After the bag is secured to the spindle by a transfer mechanism such as that described in U.S. Pat. No. 4,667,890, incorporated herein by reference, the turret is rotated 120.degree. so that the first spindle is in a winding position and the strip is wound into a coreless roll. Following completion of the roll winding, the turret rotates again to a removal station where the roll is pushed off the first spindle by a push-off palm for subsequent packaging. When the winding of the one roll is completed the leading end of the film is directed to a second spindle in the transfer position.
In some prior art winders the spindles of the machine are tapered and include a plurality of air holes through which air can be selectively injected. The taper and air injection assist in the removal of the coreless roll. Second, a belt is provided below the film path. The roll being wound on the spindle stays in contact with the belt to improve the quality of the rolled product, and as the diameter of the roll increases during winding, the belt moves to accommodate roll expansion. This bottom belt is just one of a series of bottom belts used in the prior art machine from the inlet to the outlet of the winder.
To attach the leading end of a strip to the spindle in the transfer position prior art machines use an airhorn and kick-roll mechanism. The kick-roll is a pneumatic activated roller located beneath a traveling belt at the area near the transfer location. At the time of transfer, the roller would be extended by a piston rod to quickly push against the belt to "flip" the leading edge of the strip of bags up into the air above the lower belt. At the same time, an airhorn would descend around the spindle, the airhorn being a half-cylinder containing air ports on one edge. The combination would direct the leading edge of the bag strip around the spindle and tuck it into its own nip to create the attachment. This system, while being better than earlier systems, suffers from drawbacks including ineffective transfers, such as a failure of the leading edge to tuck into its own nip. Because of the high speeds utilized in winders if the airhorn and kick-roll system failed to properly attach the moving plastic web to the spindle, a great deal of waste would occur before the next strip would arrive at the transfer position.
A winder which economically and effectively transferred a leading edge of a strip of plastic to a spindle would represent a significant advance in the art.